The present invention relates to chewing gum. More specifically, this invention relates to improved formulations for chewing gum bases and chewing gum containing highly substituted starch short chain carboxylates.
Primary components of a chewing gum typically are a water-insoluble gum base portion and a water-soluble bulking agent portion typically including a bulking agent together with minor amounts of secondary components such as flavors, colorants, water-soluble softeners, gum emulsifiers, acidulants and sensates. Typically, the water-soluble portion, sensates, and flavors dissipate during chewing and the gum base is retained in the mouth throughout the chew.
Water-insoluble gum base typically includes elastomers, elastomer solvents, softeners/emulsifiers (including fats, oils, waxes, mono- and di-glycerides), and fillers. Elastomers commonly used in gum bases are synthetic elastomers such as polyisobutylene, isobutylene-isoprene copolymers (“butyl rubber”), conventional styrene-butadiene copolymers, polyisoprene, and combinations thereof. Also, natural elastomers such as natural rubbers can be used.
Because the elastomer is an important functional component of a gum base, the characteristics of such elastomers have a significant impact on characteristics of a chewing gum composition, especially regarding those properties important to consumer acceptance. Among properties important to consumers are odor, taste, chewing properties, and mouthfeel, including the ability of a gum composition to form a cud while chewing. Furthermore, physical characteristics of the elastomer affect processibility of a gum base and of a chewing gum formulation including the gum base.
Chewing gums were originally formulated with natural gums, primarily jelutong and chicle, which were obtained by tapping rainforest rubber trees. Due to fluctuating supply and price of the natural products and increasing demand for chewing gum products, these rubbers have largely been replaced by synthetic elastomers. The elastomer most widely used currently in chewing gum is butyl rubber due to consumer acceptance of chewing properties of the resulting chewing gum product and the lack of objectionable odor or taste associated with butyl rubber. Polyisobutylene (FIB) is another elastomer frequently used in gum bases. Lower molecular weight (below 100,000 viscosity average) PIB improves compatibility of base components, modifies elasticity and softens the chewing characteristics of gum bases to which it is added. However, it is not generally usable as the sole elastomer in a gum base formula. Higher molecular weight (at least 100,000 viscosity average) PIB acts more like butyl rubber, but its use is less common. Styrene butadiene copolymer rubber (SBR) has been used successfully as an elastomer in gum products, particularly bubblegums.
The above elastomers are normally derived from a petroleum feedstock and processed to food-grade standards. Recently, consumers have expressed preference for more natural foods and a desire to minimize use of products derived from petroleum. Additionally, due to fluctuations in the price and supply of petroleum, continued availability of these food-grade elastomers has become uncertain. While some non-petroleum derived elastomers have been proposed, problems with cost, supply, texture, flavor or the use of potentially toxic solvents and reagents have precluded widespread implementation of these alternative elastomers. In this regard, it is desirable to find an inexpensive, readily available, consumer-acceptable gum base elastomer which is derived from a natural food ingredient and processed without using potentially toxic solvents and reagents.
Starch is a natural product derived from plants such as corn, arrowroot, potatoes, sago and tapioca. Starch is a polysaccharide carbohydrate with a chemical formula (C6H10O5)n, (where n is typically in the range of 200 to 600,000) consisting of a large number of anhydroglucose monosaccharide units joined together by glycoside bonds. All plant seeds and tubers contain starch which is predominantly present as amylose and amylopectin. Chemical derivatives of starch are known such as starch acetate which typically is formed by esterification of starch with acetic anhydride. Unmodified starch or conventional starch acetates are unsuitable for use in a gum base because they lack elastomeric properties and hydrophobicity required for a suitable gum base.
This invention is directed to gum bases containing plasticized short chain alkanoates of starch having a high degree of substitution and to consumer-acceptable chewing gum formulations containing such gum bases.